Electronic displays are widely used. Although in the past the use of electronic displays has been primarily limited to computing applications such as desktop computers and notebook computers, as processing power has become more readily available, such capability has been integrated into a wide variety of applications. For example, it is now common to see electronic displays in applications such as teller machines, gaming machines, automotive navigation systems, restaurant management systems, grocery store checkout lines, gas pumps, information kiosks, and hand-held data organizers to name a few.
Interactive visual displays often include some form of touch sensitive screen. Integrating touch sensitive panels with visual displays is becoming more common with the emergence of portable multimedia devices. Capacitive touch sensing techniques for touch sensitive panels involve sensing a change in a signal due to capacitive coupling created by a touch on the touch panel. An electric field is applied to electrodes on the touch panel. A touch on the touch panel couples in a capacitance that alters the electric field in the vicinity of the touch. The change in the field is detected and used to determine the touch location.